I think the demo's watcher will need your mod installed to view the demo and he will probably see the timestamp appearing during the game but i'm not sure.
if your mod is called by the server using a command console or something, it will perhaps not appear, so u can imagine a command like "makess randomnumber timestamp" send to client console and your mod will splash random number and timestamp, call sshot(); and then destroy your splash like a logo does
u can also put timestamp on a background texture that will improve the difficulty of a fake.
btw with helios hook, it's very easy to avoid this "force SS" because helios can get all infos between server and client so if he detect something like makess, he can deactive his bot during ss

theres lots of features in those hooks that clanners will like alot. radar, bright skins, glowhack to name a few. setting the aimangle low would make it harder to spot. dont think clanners wouldent use helios hook if they thought the clan they were about to play wouldent question them.

some clanners are using a private triggerbot ,passes pure+qvalidate+nbsp.
iv seen it in action. if anyone knows the name of it please do come forward.

There are two functions to make a screenshot.
SShot is used by the Bindings-Window to make a screenshot. Shot makes the actual screenshot.
SShot will set the brightness level to default, make the screenshot and reset the brightness level. This will cause a lot of lagg at least on some Direct3D systems. By using simply Shot the lagg is greatly reduced.
You should check what function you use.